#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>

int main()
{
	double sum = 0;
	double arr1[10] = { 0 };
	int len = sizeof(arr1) / sizeof(double);
	for (int i = 0; i < len; i++)
	{
		scanf("%lf", &arr1[i]);
		sum += arr1[i];
	}
	double vue = sum / len;
	printf("%lf ", vue);
}